Road constructing machine



2 Sheets-Sheet 1 Julyr 5, 1937. G. F. BULLARD ROAD CONSTRUCTING MACHINE Filed Feb. l2, 1936 July 6, 1937.

G. F. BULLARD f 2,086,469

ROAD CONST'RUCTING MACHINE Filed Feb. l2, 1956 2 Sheets-Shea?I 2 Gf. Jfuzzard F11 A mmm;

Patented July 6, 1937 UNTED STAFES ZStftQ PATENT OFElCE.

4 Claims.

This invention relates to road construction and more particularly to an attachment for the scraper blade or mold boardof standard road grading machines.

In certain sections of this country, excellent roads are produced at low cost by a method commonly called the mix-in-place operation. This method consists in mixing bituminous material, either cut-back asphalt or tar, with aggregate or existing road material, which is generally sand, working it into the road surface by means of discs, plows and blades until a homogeneous mixture is obtained and finally rolling and sealing the surface to form a smooth roadway. This method is quite satisfactory when the work` is done in dry warm Weather, but is unsuitable when the weather is cool or during seasons of wet weather.

The object of my invention is to provide means for drying the aggregate and heating the bituminous element of the road mix during the usual blade scraping and road working operations, to thereby produce a very fast and thorough mixing of the bituminous material and the road aggregate together with a more homogeneous resulting mix.

In the following detailed description of my invention, I shall refer to the accompanying drawings, in which- Figure 1 is a fragmentary side elevation of the supporting framework of a standard road grader showing my blade-heating chamber attached to the scraper blade.

Figure 2 is a transverse View on the line 2 2 of Fig. 1.

Figure 3 is sectional View taken on the line 3 3 of Figure 4 showing one of the burners for heating the blade heating chamber.

Figure 4 is a schematic View showing a rear elevation of the blade heating chamber and the manner of supplying the oil under pressure to the burners.

Figure 5 is a schematic perspective View illustrating the manner in which the heated blade operates upon the mixture of bituminous material and road aggregate.

All road engineers are familiar with the construction and operation of standard road grading machines and hence it is unnecessary to include a description herein. I have shown the scraper blade I attached to the supporting frame in the usual manner. As is well known, the blade may be adjusted forward or backward in a vertical plane to the desired angle with the road surface and the blade support may be swung forwardly (Cl. Bt-44) or rearwardly and elevated or lowered as desired.

The casing or housing of the blade heating chamber l2 may be constructed of cast iron or of sheet steel bolted to the rear side of the blade and braced by straps l/l. A plurality of extensions i5 are provided at equal distances along the heating chamber to form inlets for kerosene burners The burners are connected in multiple to a supply pipe il, leading to a fuel tank I8 located at the rear of the blade frame. An air compressor 2G and reserve air tank 2l maintain a suitable pressure in the fuel tank.

The mold board and blade it) are protected from the direct blast of the burners by perforated baille plates positioned in front of each burner. The portion of the rocker arms 26 within the heating chamber may also be protected by asbestos walled chambers 23. Draft vents 26 are provided at equal distances from the burner inlets. In this manner the heat is evenly distributed through the chamber and the blade is uniformly heated throughout its extent.

The temperature of the scraper blade or mold board l] is maintained between 275 and 350 Fahrenheit. As the road grader travels over the road the blade gathers the mixture of aggregate and bituminous material and causes it to travel toward the trailing end of the blade as indicated in Fig. 5. As the material in front of the blade is constantly pushed upward and continuously tumbles from the top, the particles of the aggregate are brought again and again into contact with the hot blade. This tumbling action is enhanced by the concave shape of the blade. The particles of the aggregate are caused to intermingle by their travel transversely toward the trailing end of the blade. The heat of the blade drives off moisture from the aggregate and causes the particles to become heated. The bitumen constituent is softened so that it flows more readily intointimate Contact with the particles of the heated aggregate and becomes thoroughly incorporated throughout the resulting homogeneous mixture. After the rolling operation, a roadway prepared in the manner described not only presents a smooth surface but is exceedingly compact and wear resisting.

It will be evident to engineers that my apparatus does not interfere with the normal operation of the road grading machine and requires no additional power. It greatly enhances the eciency of the mixing function of the machine by drying the aggregate, improves the homogeneity of the mixture by softening or rendering more fluid the bituminous constituent and bringing it into intimate contact with the heated particles of the aggregate. Finally, my invention enables roadmaking operation to be successfully conducted when the Weather is cool and to some extent, when it is wet.

I claim:-

1. In a machine for road construction, the combination with a concave scraper blade carried by said machine and arranged for adjustment with the surface of the road, a heating chamber secured to the rear side of the blade, means for continuously heating the air in said chamber and causing it to continuously impinge upon the rear side of said blade.

2. In a machine for road construction, the combination with a scraper blade carried by said machine and arranged for adjustment with the surface of the road and constructed to gather material therefrom and cause a mixing action thereof, a heating chamber secured to the rear side of the blade, a plurality of burners spaced at intervals and connected to said chamber, and means for supplying fuel to said burners, said burners being positioned and arranged to cause the heated air to impinge Vupon and circulate over the surface of the rear side of said blade.

3. In a machine for road construction, the combination with a concave scraper blade, of means for heating the blade comprising a heating chamber in juxtaposition With the rear` side of the blade, a plurality of burners communicating with said chamber, means for supplying iuel to said burners, and means for equalizing the heat transmitted to the blade comprising a nre-resistant screen positioned in front of each burner.

4. In a machine for road construction, the combination with a concave scraper blade, of means for heating the blade comprising a heating chamber in juxtaposition with the rear side of the blade, a plurality of burners communicating with said chamber, means for supplying fuel to said burners, and means for equalizing the heat transmitted to the blade comprising a chamber having non-combustible Walls positioned in front of each burner and vent openings equally spaced from the burners.

GEORGE F. BULLARD. 

